Catalysts are important components of many chemical manufacturing processes, and may typically be used to accelerate the rate of the reaction in question and/or to increase the selectivity or efficiency towards the desired product(s). Utilized in connection with many reactions, catalysts find particular advantageous use in the epoxidation of olefins, and even more particularly in the epoxidation of alkylenes, a process of significant commercial importance in the commodity chemical business. In such epoxidation reactions, a feed containing at least the olefin/alkylene and oxygen is contacted with a catalyst causing the formation of the corresponding olefin oxide. Typically, catalysts used in alkylene epoxidation comprise a catalytic species deposited on a suitable support/carrier alone or in combination with one or more promoters.
Those of skill in the art have actively sought improvements in the selectivity and useful life of epoxidation catalysts for some time, since even incremental decreases in selectivity can be commercially detrimental. Further, catalyst failure and the changeout that it requires represent a substantial cost in epoxidation processes.
Research in this area has been wide ranging, and improvements that may provide the catalysts with increased efficiency and/or an extended useful life have been sought in the areas of components of the catalyst, e.g., carriers, promoters, and catalytic species, methods of making the catalyst and even the epoxidation processes themselves. However, it is often the case that adjustments in one or more of these may result in an improvement in one of catalyst efficiency, activity, or lifetime while yet resulting in a concurrent decrement in another. Or, any such adjustments may require conditions that cannot be produced within the epoxidation process, or if reproducible therewithin, require a reduction, or complete shut-down, in the production of the epoxidation product. Finally, once a decrease in catalyst selectivity has been detected, it can be difficult to enhance the selectivity of the catalyst or increase the catalyst lifetime by an appreciable amount, or in a commercially reasonable fashion, while yet maintaining the desired manufacturing output.
Desirably, methods would be provided that could be utilized to select catalysts, or carriers upon which the catalysts are to be based, that will exhibit a more desirable selectivity and or catalyst lifetime once in use, prior to their use. In this way, costly disruptions to manufacturing can be avoided.